In bandwidth-guaranteed networks typified by NGNs (Next Generation Networks) a session control protocol is used to perform accounting, authentication, and reservation of communication bandwidth, etc. So far, the session control protocol has often been used to implement one-to-one communication such as telephone, and has rarely been utilized to control a session in one-to-many communication such as multicast. Because of this, it has been difficult to implement accounting, authentication, and reserving communication bandwidth in a multicast communication.
For example, although securement of the bandwidth of multicast communication by RSVP (Resource Reservation Protocol) has been under study and planning, it has not yet been widely used because of the difficulty of installing. Further, since multicast protocols typified by the IGMP (Internet group Management Protocol) cannot perform notification of communication bandwidth information, using multicast protocols to reserve communication bandwidth is difficult.